1. Field of the Invention
The present invention relates to a solid-state light-emitting element, a light-emitting device including the light-emitting element, and a lighting device including the light-emitting device.
2. Description of the Related Art
A solid-state light-emitting element emits light in a region with a higher refractive index than the air; thus, the solid-state light-emitting element has a problem that the light extraction efficiency thereof is lower than 100% due to the condition by which total reflection occurs at the interface between the region with a high refractive index and the air when light is extracted to the air.
In order to solve the problem, a light-emitting element in which an uneven structure body with a high refractive index is provided on a surface of a region with a high refractive index of a solid-state light-emitting element to extract light to the air side, or the like has been reported.
For example, in Non-Patent Document 1, as a means for improving light extraction efficiency of a light-emitting element, a structure in which a high refractive index glass substrate and a high refractive index lens are combined and a structure in which an uneven structure is provided at the interface between a high refractive index glass substrate and the air are employed.    [Non-Patent Document 1] White organic light-emitting diodes with fluorescent tube efficiency, Nature, May 14, 2009, Vol. 459, pp. 234-239